Manufacturing method for a secure-digital (SD) flash card with slanted asymmetric circuit board

ABSTRACT

A flash-memory device has a printed-circuit board assembly (PCBA) with a PCB with a flash-memory chip and a controller chip. The controller chip includes an input/output interface circuit to an external computer over a Secure-Digital (SD) interface, and a processing unit to read blocks of data from the flash-memory chip. The PCBA is encased inside an upper case and a lower case, with SD contact pads on the PCB that fit through contact openings in the upper case. Supporting end ribs under each of the SD contact pads and middle ribs support the PCB at a slanted angle to the centerline of the device. The PCB slants upward at the far end to allow more thickness for the chips mounted to the bottom surface of the PCB, and slants downward at the insertion end to position the SD contact pads near the centerline.

RELATED APPLICATION

This application is a divisional of U.S. Ser. No. 11/309,844, filed Oct.11, 2006, now U.S. Pat. No. 7,535,088, which is a continuation-in-part(CIP) of “Electronic Data Storage Medium with Fingerprint VerificationCapability”, U.S. Ser. No. 09/478,720, filed Jan. 6, 2000, and is acontinuation-in-part (CIP) of “Removable flash integrated memory modulecard and method of manufacture”, U.S. patent application Ser. No.10/913,868, filed Aug. 6, 2004.

FIELD OF THE INVENTION

This invention relates to flash-memory cards, and more particularly tomanufacturing a flash card with a slanted printed-circuit board (PCB).

BACKGROUND OF THE INVENTION

Flash-memory cards using standards such as compact-flash (CF),Multi-Media Card/Secure Digital (MMC/SD), and Sony's MemoryStick arepopular today. Such flash cards may be used in consumer devices such asdigital cameras, music players, phones, palm or other portablecomputers, and may be inserted into personal computers and printers.Various extensions of these standards exist, such as Super Digital, anextension of Secure Digital (SD) that does not have all the securityfeatures and digital-rights management features of SD. MMC/SD is populardue to its small size, about the size of a postage stamp.

Data files stored on such as flash card, or on a more traditional floppydisk or diskette may require a password for access, or may useencryption to secure the data within the file. Confidential documentscan be delivered over a network by adding safety seals and impressions.However, the confidential data is at risk due to breaking of thepasswords, encryption codes, safety seals and impressions, therebyresulting in unsecure transfer of the information.

The parent application disclosed an electronic data storage medium thathad fingerprint verification capability. FIG. 1 is a schematic circuitblock diagram illustrating an electronic data storage medium disclosedin the parent application.

The electronic data storage medium with fingerprint verificationcapability can be accessed by external computer 9 using input/outputinterface circuit 5, which may use a Personal-Computer Memory CardInternational Association (PCMCIA), RS-232, or similar interface tocommunicate. The electronic data storage medium can be located inside oroutside of the external computer.

The electronic data storage medium with fingerprint verificationcapability is packaged in card body 1, and includes processing unit 2,memory device 3, fingerprint sensor 4, input/output interface circuit 5,display unit 6, power source 7, and function key set 8.

Memory device 3 can be a flash memory device that stores data files.Fingerprint sensor 4 scans a fingerprint of a user to generatefingerprint scan data. Processing unit 2 connects to other componentsand can operate in various modes, such as a programming mode, a dataretrieving mode, and a data resetting mode. Power source 7 supplieselectrical power to processing unit 2. Function key set 8 allows theuser to input a password that is verified by processing unit 2. Displayunit 6 shows the operating status of the electronic data storage medium.

The electronic data storage medium may be a subset of the electronicdata storage medium with fingerprint verification capability. Theelectronic data storage medium is packaged in card body 1, and includesprocessing unit 2, memory device 3, and input/output interface circuit5. While such an electronic data storage medium is useful, manufacturingmethods and product designs are desired that can be cost-effectivelyproduced. In particular, designs for making the card body or casing thatencapsulates the electronic components are desired. To reduce the costand size, designs of the electronic data storage medium that eliminatesome costly components, such as the fingerprint sensor, function keyset, and display, are desirable. An external power source may furtherreduce costs and size. Such device designs can allow a low-costelectronic data storage medium to be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic circuit block diagram illustrating an electronicdata storage medium disclosed in the parent application.

FIG. 2 shows a parts view of a Secure-Digital flash card assembled usinga snap-coupled process.

FIGS. 3A-B show the circuit-board assembly in detail.

FIGS. 4A-B show detailed views of the upper and lower cases.

FIGS. 5A-B show views of a final assembled SD flash card.

FIGS. 6A-B show views of the circuit-board assembly.

FIG. 7 is a cross-sectional diagram highlighting the slanting of thecircuit board.

FIG. 8 shows end ribs formed on the lower case support the SD contactpads.

DETAILED DESCRIPTION

The present invention relates to an improvement in flash-memory cards.The following description is presented to enable one of ordinary skillin the art to make and use the invention as provided in the context of aparticular application and its requirements. Various modifications tothe preferred embodiment will be apparent to those with skill in theart, and the general principles defined herein may be applied to otherembodiments. Therefore, the present invention is not intended to belimited to the particular embodiments shown and described, but is to beaccorded the widest scope consistent with the principles and novelfeatures herein disclosed.

The inventors have developed a variety of manufacturing methods forelectronic data storage medium devices such as flash-memory cards thatcan replace hard disk drives with solid-state flash memory. Flash memorychips currently employ electrically-erasable programmable read-onlymemory (EEPROM) are the primary storage medium. Such flash memory ismore rugged than rotating magnetic disks.

The inventors have realized that the card body may be constructed from atwo-piece casing that encloses a printed-circuit board assembly (PCBA)that has a circuit board with flash-memory and controller chips mountedthereon. The two-piece casing can be assembled together and sealed in avariety of ways, such as with snaps, tabs and slots, ultrasonic ridges,adhesives, and screw fasteners.

The inventors have further realized that the card body can conform toexisting flash-card standards, such as Secure Digital (SD). However,Secure Digital is a particularly thin and flat standard compared toother standards such as Compact Flash. Being able to mount the chips ona PCB within such as SD card is challenging. However, the inventors havediscovered that the PCB inside a SD card may be slanted within the SDcard body for a better fit. The slanting of the PCB allows theflash-memory and controller chips to be mounted on one side, and themetal contacts for the SD standard to be on the other side of the PCB.The PCB is tilted to allow both the chips and the contact pads to fitwithin the card body without otherwise increasing the thickness of thecard body.

FIG. 2 shows a parts view of a Secure-Digital flash card assembled usinga snap-coupled process. PCBA 41 is enclosed by upper case 20 and lowercase 30. PCBA 41 is a circuit board such as a printed-circuit board(PCB) with wiring traces, and has a flash-memory chip and a controllerchip and components soldered to the bottom surface (hidden from thisview) of the circuit board. PCBA 41 also has SD contact pads 42 formedalong the front edge of the circuit board. SD contact pads 42 mate withsocket pads on a SD socket that the Secure-Digital flash card fits into,such as on a host or in an electronic device.

Upper case 20 has contact openings 26 between dividers 22 along thefront side. SD contact pads 42 are exposed by contact openings 26 whenPCBA 41 is assembled into upper case 20, thus allowing SD contact pads42 to make electrical connection when inserted into an SD socket.

During assembly, PCBA 41 is fitted inside upper case 20. PCBA 41 may befitted at a slanting angle within upper case 20 (See FIG. 7) to allow SDcontact pads 42 to fit within contact openings 26 while still havingroom within upper case 20 and lower case 30 for chips mounted to thebottom side of PCBA 41. The slanting angle may be 1-2 degrees in someembodiments, depending on the length of and the thickness between theupper and lower cases.

The sub-assembly of PCBA 41 inside upper case 20 is then fitted intolower case 30. Lower case 30 is slightly larger than upper case 20 sothat the side-walls of upper case 20 fit inside the side-walls of lowercase 30. Snap-tabs 24 on the outer perimeter of upper case 20 fit intoslots 34 formed on the inner side-walls of lower case 30. When uppercase 20 is fully inserted into lower case 30, snap-tabs 24 snap intoslots 34, locking upper case 20 into lower case 30. PCBA 41 is thusencased within upper case 20 and lower case 30.

Since PCBA 41 may be at a slanting angle within upper case 20 and lowercase 30, supporting ribs may be added to lower case 30 to support PCBA41 at this slanting angle. Supporting ribs 36 are formed at aboutone-third of the device's length within lower case 30, while end ribs 32are formed closer to the insertion end of lower case 30.

Both supporting ribs 36 and end ribs 32 may touch the bottom surface ofPCBA 41, providing support between PCBA 41 and lower case 30. End ribs32 are shorter than supporting ribs 36, to conform to the slanting angleof PCBA 41, which is lower within lower case 30 at the insertion endthan at the far end opposite the insertion end. This slanting angleallows for thicker chips at the far end of PCBA 41, on the bottomsurface of PCBA 41.

SD contact pads 42 at the insertion end of PCBA 41 are lowered withinthe casing because contact openings 26 in upper case 20 force SD contactpads 42 to be lower within the casing (See FIG. 4A and FIG. 5B).

Supporting ribs 36 and end ribs 32 can be formed as raised ridges onlower case 30. Supporting ribs 36 and end ribs 32 can be sufficientlytall to reach the lower surface of the circuit board of PCBA 41 to addsupport of the final assembled flash drive. Supporting ribs 36 and endribs 32 can thus prevent the middle of lower case 30 from flexing ordimpling inward when a user pinches together the centers of upper case20 and lower case 30 of the assembled device. Supporting ribs 36 and endribs 32 can thus give the finished device a more rugged and solid feelin the user's hands, increasing the user's perception of quality of thedevice.

Switch 70 is inserted onto a switch-slot on lower case 30. Switch 70 canbe a slidable switch that is used to activate write or erasureprotection, making the flash memory read-only when switch 70 isactivated by the user. Switch 70 may be attached to lower case 30 beforeassembly or after assembly.

Contact layers of adhesive may be used to secure the upper and lowercases together to enclose PCBA 41. Upper adhesive film 50 bonds uppercase 20 to PCBA 41, while lower adhesive film 60 bonds lower case 30 toPCBA 41.

During assembly, upper adhesive film 50 is placed inside upper case 20,and PCBA 41 is fitted inside upper case 20. PCBA 41 makes contact withupper adhesive film 50. Lower adhesive film 60 is then placed insidelower case 30, and the sub-assembly of upper case 20 and PCBA 41 isfitted into lower case 30 and snapped together.

Upper adhesive film 50 and lower adhesive film 60 can be a film with aheat-activated adhesive, such as a thermal-bond film (for example,product number TBF668 produced by 3M). The adhesive is then compressedbetween upper case 20, lower case 30, and PCBA 41, and the assembly isheld in the compressed state using a fixture or by snap-tabs 24 lockedinto slots 34. The fixture or device is then passed through an ovenmaintained at a specified temperature to activate or cure the adhesive.The oven temperature can be at or lower than the maximum safe operatingtemperature for the memory module components.

An advantage of heat-activated adhesives is that they can be removed byheating, and thus enable reworking of flash devices. To separate uppercase 20 from lower case 30 during re-work, a heating machine with atemperature of about 150° C. may be used for several seconds to removeor loosen the adhesives.

FIGS. 3A-B show the circuit-board assembly in detail. In the top view ofFIG. 3A, PCBA 41 includes a circuit board with wiring traces on severallayers, and vias or other inter-layer connections. SD contact pads 42are formed along the front (insertion) end of circuit board 40 using alayout dictated by the SD standard.

In the bottom view of FIG. 3B, flash-memory chip 44 is mounted to thebottom surface of circuit board 40. Controller chip 46 is also mountedto circuit board 40, between flash-memory chip 44 and the insertion endof circuit board 40, which has SD contact pads 42 on the top surface asshown in FIG. 3A. Controller chip 46 can have an SD or other businterface to communicate with a host over SD contact pads 42. Controllerchip 46 can also have a flash controller that reads, erases, and writesblocks of data to flash-memory chip 44, perhaps including wear-levelingand address re-mapping logic and tables.

Supporting ribs 36 and end ribs 32 of lower case 30 make contact withthe bottom surface of circuit board 40, at the area on circuit board 40between controller chip 46 and the insertion (front) end. This contactallows SD contact pads 42 to be in downward position within upper case20, as required by the SD specification, yet also allows the far (back)end of circuit board 40 to slant upward, making more room for chips 44,46.

FIGS. 4A-B show detailed views of the upper and lower cases. FIG. 4Ashows a top view of upper case 20, while FIG. 4B shows a top view oflower case 30. In FIG. 4A, upper case 20 has contact openings 26 betweendividers 22 along the front side. SD contact pads 42 (not shown) areexposed by contact openings 26 when PCBA 41 is assembled into upper case20, thus allowing SD contact pads 42 to make electrical connection wheninserted into an SD socket.

In FIG. 4B, lower case 30 is slightly larger than upper case 20 so thatthe side-walls of upper case 20 fit inside the side-walls of lower case30. Snap-tabs 24 on the outer perimeter of upper case 20 fit into slots34 formed on the inner side-walls of lower case 30. When upper case 20is fully inserted into lower case 30, snap-tabs 24 snap into slots 34,locking upper case 20 into lower case 30. PCBA 41 is thus encased withinupper case 20 and lower case 30.

Since PCBA 41 may be at a slanting angle within upper case 20 and lowercase 30, supporting ribs may be added to lower case 30 to support PCBA41 at this slanting angle. Supporting ribs 36 are formed at aboutone-third of the device's length within lower case 30, while end ribs 32are formed closer to the insertion end of lower case 30. End ribs 32 fitunder and support SD contact pads 42 on the assembled device and may bemade wider and stronger to support external pressure that may be appliedon SD contact pads 42 during rough use. Ideally, end ribs 32 may each belocated under the center of each of SD contact pads 42.

Both supporting ribs 36 and end ribs 32 may touch the bottom surface ofPCBA 41, providing support between PCBA 41 and lower case 30. End ribs32 are shorter than supporting ribs 36, to conform to the slanting angleof PCBA 41, which is lower within lower case 30 at the insertion endthan at the far end opposite the insertion end. This slanting angleallows for thicker chips at the far end of PCBA 41, on the bottomsurface of PCBA 41.

Front teeth 33 on lower case 30 fit in front of dividers 22 on the finalassembled device. Since upper case 20 fits within lower case 30, frontteeth 33 fit in front of dividers 22. Switch mount 37 is formed on theside wall of lower case 30. Switch mount 37 is for receiving switch 70.Switch 70 may slide along switch mount 37. Holes 74 formed on back-sidewalls of lower case 30 are for receiving an external string or chain,such as a key chain for transporting the device.

FIGS. 5A-B show views of a final assembled SD flash card. FIG. 5A showsa bottom view from the back of the final assembled flash-card device,with lower case 30 covering PCBA 41. The side walls visible are fromlower case 30, since lower case 30 fits over upper case 20. Switch 70 isvisible on one side, and holes 74 for receiving a chain or string in theback of the device.

FIG. 5B shows a top view of the front (insertion) end of the finalassembled flash-card device, with upper case 20 covering PCBA 41. SDcontact pads 42 extend from front openings in upper case 20. The sidewalls visible are part of lower case 30. SD contact pads 42 can beinserted into a SD socket such as on a host computer, and can be read asa mass-storage device, replacing a rotating hard disk. Mass-storagedevices are read in large blocks or streams of data, rather than asrandomly-addressable words.

FIGS. 6A-B show views of the circuit-board assembly. In the top view ofFIG. 6A, PCBA 41 includes a circuit board with wiring traces on severallayers, and vias or other inter-layer connections. SD contact pads 42are formed along the front (insertion) end of circuit board 40 using alayout dictated by the SD standard. A small portion of flash-memory chip44 is visible underneath circuit board 40 in this view.

In the bottom view of FIG. 6B, flash-memory chip 44 is mounted to thebottom surface of circuit board 40. Controller chip 46 is also mountedto circuit board 40, between flash-memory chip 44 and the insertion endof circuit board 40, which has SD contact pads 42 on the top surface asshown in FIG. 3A. Controller chip 46 can have an SD or other businterface to communicate with a host over SD contact pads 42. Controllerchip 46 can also have a flash controller that reads, erases, and writesblocks of data to flash-memory chip 44, perhaps including wear-levelingand address re-mapping logic and tables. Other components 48 may includecapacitors, resistors, buffers, or other chips.

Supporting ribs 36 and end ribs 32 of lower case 30 make contact withthe bottom surface of circuit board 40, at the area on circuit board 40between controller chip 46 and the insertion (front) end. This contactallows SD contact pads 42 to be in downward position within upper case20, as required by the SD specification, yet also allows the far (back)end of circuit board 40 to slant upward, making more room for chips 44,46.

FIG. 7 is a cross-sectional diagram highlighting the slanting of thecircuit board. Circuit board 40 has flash-memory chip 44 and controllerchip 46 and other components mounted to the bottom surface by the farend, while SD contact pads 42 are formed on the top surface by theinsertion end. Lower case 30 and upper case 20 encase circuit board 40and its components.

Contact openings 26 in upper case 20 force the upper surface of SDcontact pads 42 to be positioned at about half of the thickness of theSD device. Dividers 22 between contact openings 26 have a greater heightor thickness.

Since chips 44, 46 are relatively thick, circuit board 40 is slantedupward at the far end, allowing more space for chips 44, 46. Theposition of the insertion end of circuit board 40 with SD contact pads42 is fixed by the SD mechanical specification to be near the devicecenter-line, at about half the device thickness. Thus circuit board 40is near the center-line at the insertion end, but slants upward towardthe far end, providing additional space for chips 44, 46. This slantingof circuit board 40 more efficiently uses the volume within upper andlower case 20, 30. If circuit board 40 were to have no slant and remainat the device center-line, chips 44, 46 would extend above upper case20, requiring that upper case 20 be raised, increasing device thickness.

FIG. 8 shows end ribs formed on the lower case support the SD contactpads. End ribs 32 are formed on lower case 30, below SD contact pads 42.Supporting ribs 36 are formed farther back in the device, betweencontroller chip 46 and SD contact pads 42. Both end ribs 32 andsupporting ribs 36 are formed on the inside of lower case 30, and arelocated under the bottom surface of circuit board 40.

Advantages of the flash card device include a compact size, lightweight, low power consumption, and the reliability of completelysolid-state components with no moving parts. There is no mechanism formechanical fatigue since the moving parts of the hard disk are replacedby flash-memory chips, which offer superb shock and vibrationresistance.

Alternate Embodiments

Several other embodiments are contemplated by the inventors. Forexample, while a connector and a controller chip for the SD protocol hasbeen described, other bus protocols and physical connectors could besubstituted, such as small-computer system interface (SCSI), compactflash, serial AT attachment (SATA), and PCI Express, ExpressCard,Firewire (IEEE 1394), integrated device electronics (IDE), Multi-MediaCard (MMC), etc. While Secure-Digital (SD) has been described, othervariations of SD may be substituted, such as Super Digital, which maynot have some security features of SD.

Controller chip 46 and flash-memory chip 44 may be packaged in a varietyof integrated circuit packages, such as Thin-Outline Small Package(TOSP), Ball-Grid Array (BGA), Chip-On-Board (COB), or in a multi-chippackage.

The upper and lower cases could be formed from metal in someembodiments, such as when using screws, or could be plastic, such as forultrasonic bonding. Combinations of plastic and metal could be used. Theform factor for the flash-card device could vary.

Directional terms such as upper, lower, up, down, top, bottom, etc. arerelative and changeable as the device is rotated, flipped over, etc.These terms are useful for describing the device but are not intended tobe absolutes. Some embodiments may have chips or other componentsmounted on only one side of the circuit board, while other embodimentsmay have components mounted on both sides. In some embodiments the lowercase could be smaller than the upper case, or vice-versa.

An alternative process to the above heat-activated adhesive film is touse high viscosity adhesives. The adhesive can be applied to the casesurface by manual or automatic using dispensing machine. Afterdispensing adhesives onto the case surface, immediately press the caseagainst PCBA. A press fixture may be used to hold the case and PCBA inposition. The curing time is about several minutes.

Various combinations of processes may be used. For example, the adhesivefilms may be used with the screw-together method rather than withsnap-tabs. Alignment sockets may be added to other embodiments. Centerlines or more numerous ridges may be added to stiffen the upper or lowercases. Various cosmetic features, decals, and indicia may be added.

Rather than mount packaged IC's onto the surfaces of the circuit board,unpackaged die may be mounted using die-bonding techniques. Usingunpackaged die rather than packaged die may reduce the size and weightof the PCBA.

Snap-tabs with more complex movable latching teeth or extensions orlocking portions may also be used in many variations. Differentthicknesses and dimensions can be substituted for the examples given.The number and arrangement of chips may vary.

Various design features such as cutouts, holes, supporting undersideribs, or bumps can be added. A variety of materials may be used for theconnector, circuit boards, metal pads, cases, etc. Plastic cases canhave a variety of shapes and may partially or fully cover differentparts of the circuit board and connector, and can form part of theconnector itself. Metal covers rather than plastic may be used in someembodiments. Various features can have a variety of shapes and sizes.Oval, round, square, rectangular, trapezoidal, and other shapes may beused.

Rather than use the flash-card device only for flash-memory storage,additional features may be added. For example, a music player mayinclude a controller for playing audio from MP3 data stored in the flashmemory. An audio jack may be added to the device to allow a user to plugin headphones to listen to the music. A wireless transmitter such as aBlueTooth transmitter may be added to the device to connect to wirelessheadphones rather than using the audio jack. Infrared transmitters suchas for IrDA may also be added. A BlueTooth transceiver to a wirelessmouse, PDA, keyboard, printer, digital camera, MP3 player, or otherwireless device may also be added. The BlueTooth transceiver couldreplace the connector as the primary connector. A Bluetooth adapterdevice could have a connector, a RF (Radio Frequency) transceiver, abaseband controller, an antenna, a flash memory (EEPROM), a voltageregulator, a crystal, a LED (Light Emitted Diode), resistors, capacitorsand inductors. These components may be mounted on the PCB before beingenclosed into a plastic or metallic enclosure. Of course, the size ofthe flash-card device may increase.

A fingerprint scanner, display, keypad, power supply, or otheraccessories could be added to the flash-drive device with suitablechanges to the casing to allow space and user access to these devices ifneeded. Alternately, the flash device may delete these components andjust have input/output interface circuit 5, processing unit 2, and aflash memory device in the arrangement of FIG. 1. Power may be suppliedthrough the connector. Input/output interface circuit 5 may beintegrated with processing unit 2 as controller chip 45.

An indicator lamp such as an light-emitting diode (LED) could be addedto the PCBA. The case may have an opening, thinning of the plastic, or alens to allow light from the indicator lamp to shine through the case. Alight pipe or light channel could be added.

Any advantages and benefits described may not apply to all embodimentsof the invention. When the word “means” is recited in a claim element,Applicant intends for the claim element to fall under 35 USC Sect. 112,paragraph 6. Often a label of one or more words precedes the word“means”. The word or words preceding the word “means” is a labelintended to ease referencing of claim elements and is not intended toconvey a structural limitation. Such means-plus-function claims areintended to cover not only the structures described herein forperforming the function and their structural equivalents, but alsoequivalent structures. For example, although a nail and a screw havedifferent structures, they are equivalent structures since they bothperform the function of fastening. Claims that do not use the word“means” are not intended to fall under 35 USC Sect. 112, paragraph 6.Signals are typically electronic signals, but may be optical signalssuch as can be carried over a fiber optic line.

The foregoing description of the embodiments of the invention has beenpresented for the purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed. Many modifications and variations are possible in light ofthe above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto.

1. A method for manufacturing a flash-memory device comprising: formingcontact pads on an upper surface of a printed-circuit board (PCB);forming a PCB assembly by soldering a flash-memory chip onto a lowersurface of the PCB and soldering a controller chip to the lower surfaceof the PCB; wherein the contact pads are for carrying signals from anexternal computer to the controller chip to instruct the controller chipto read blocks of data from the flash-memory chips; forming an uppercase by molding plastic; forming locking tabs on the upper case whenforming the upper case; forming a lower case by molding plastic, thelower case having an outside surface as a largest external surface ofthe lower case; forming engagement slots on the lower case when formingthe lower case; forming supporting ribs on the lower case when formingthe lower case, the supporting ribs for supporting the PCB assembly at aslanted angle within the lower case wherein the upper and lower surfacesof the PCB are not parallel with the outside surface of the lower case;fitting the PCB assembly into the upper case to form a sub-assembly ofthe PCB assembly and the upper case; sliding the upper case into thelower case until the locking tabs on the upper case snap into theengagement slots on the lower case to secure the upper case to the lowercase; wherein the upper and lower surfaces of the PCB are not parallelwith the outside surface of the lower case; whereby the PCB assembly isat the slanted angle within the lower case when the flash-memory deviceis assembled using a snap-together process.
 2. The method of claim 1further comprising: inserting an upper adhesive film between the PCBassembly and the upper case during assembly; inserting a lower adhesivefilm between the PCB assembly and the lower case during assembly;whereby the upper adhesive film bonds the upper case to the PCB assemblyand the lower adhesive film bonds the lower case to the PCB assemblyduring assembly.
 3. The method of claim 1 further comprising: formingend ribs inside the lower case when forming the lower case, wherein eachend rib is located directly underneath a contact pad on the uppersurface of the PCB when assembled; wherein the end ribs increaserigidity of the contact pads within the lower case.
 4. The method ofclaim 1 wherein the contact pads are below a center-line between theupper case and the lower case when assembled; wherein the PCB is slantedupward and is above the center-line at the flash-memory chip, wherebythe PCB straddles the center-line for an asymmetric flash-memory devicedesign.